Composite Sections for Aircraft Fuselages and Other Structures, and Methods and Systems for Manufacturing Such Sections

ABSTRACT

Composite sections for aircraft fuselages and other structures, and methods and systems for manufacturing such sections, are disclosed herein. A method for manufacturing a shell structure in accordance with one embodiment of the invention includes applying composite material to an interior mold surface of a tool to form a skin extending 360 degrees around an axis. The method can further include positioning a plurality of stiffeners on an inner surface of the skin. After the stiffeners have been positioned, a vacuum bag can be installed over the stiffeners and evacuated to press the stiffeners and the skin outwardly against the interior mold surface of the tool. Next, the skin/stiffener combination can be cocured to bond the stiffeners to the skin and harden the shell structure.

TECHNICAL FIELD

The following disclosure relates generally to composite structures and,more particularly, to methods and systems for manufacturing compositesections for aircraft fuselages and other structures.

BACKGROUND

The primary structural elements of passenger jets and other largeaircraft are typically made from metal. Fuselage shells for suchaircraft, for example, are typically made from high-strength aluminumalloys. Although some composite materials may offer higherstrength-to-weight ratios than aluminum alloys, there are oftendifficulties with manufacturing large shell structures from compositematerials. For this reason, the use of composite materials for fuselageshells has mostly been limited to smaller aircraft, such as fighteraircraft, high-performance private aircraft, and business jets.

Composite materials typically include glass, carbon, or polyaramidefibers in a matrix of epoxy or other resin. One known method formanufacturing business jet airframes with composite materials isemployed by the Raytheon Aircraft Company of Wichita, Kansas, tomanufacture the Premier I and Hawker Horizon business jets. This methodinvolves wrapping carbon fibers around a rotating mandrel with anautomated fiber placement system. The mandrel provides the basic shapeof a longitudinal fuselage section. The carbon fibers are preimpregnatedwith a thermoset epoxy resin, and are applied over the rotating mandrelin multiple plies to form an interior skin of the fuselage section. Theinterior skin is then covered with a layer of honeycomb core. The fiberplacement system then applies additional plies of preimpregnated carbonfibers over the honeycomb core to form an exterior skin that results ina composite sandwich structure.

The Premier I fuselage includes two 360-degree sections formed in theforegoing manner. The Hawker Horizon fuselage includes three suchsections formed in this manner. The two 70-inch diameter sections of thePremier I fuselage are riveted and then bonded together at acircumferential splice joint to form the complete fuselage structure.The much larger Hawker Horizon fuselage, with an 84-inch diameter, usesaluminum splice plates at two circumferential joints to join the threefuselage sections together into a complete structure. (See RaytheonAircraft news release athttp://www.beechcraft.de/presse/2000/100900b.htm entitled “RAYTHEONAIRCRAFTS HAWKER HORIZON REACHES FUSELAGE MILESTONE,” Oct. 9, 2000).

Filament winding, fiber placement, and tape laying are three knownmethods for applying unidirectional composite fibers to a rotatingmandrel to form a continuous cylindrical skin. In a filament windingprocess, the mandrel is typically suspended horizontally between endsupports. The mandrel rotates about the horizontal axis as a fiberapplication instrument moves back and forth along the length of themandrel, placing fiber onto the mandrel in a predeterminedconfiguration. In most applications, the filament winding apparatuspasses the fiber material through a resin “bath” just before thematerial touches the mandrel. This is called “wet winding.” In otherapplications, the fiber has been preimpregnated with resin, eliminatingthe need for the resin bath. Following oven or autoclave curing of theresin, the mandrel can remain in place and become part of the woundcomponent, or it can be removed.

The fiber placement process typically involves the automated placementof multiple “tows” (i.e., untwisted bundles of continuous filaments,such as carbon or graphite fibers, preimpregnated with a thermoset resinmaterial such as epoxy) tape, or slit tape onto a rotating mandrel athigh speed. A typical tow is between about 0.12″ and 0.25″ wide whenflattened. Conventional fiber placement machines dispense multiple towsto a movable payoff head that collimates the tows (i.e., renders thetows parallel) and applies the tows to the rotating mandrel surfaceusing one or more compaction rollers that compress the tows against thesurface. In addition, such machines typically include means fordispensing, clamping, cutting and restarting individual tows duringplacement.

Tape laying is similar to the fiber placement process described aboveexcept that preimpregnated fiber tape, rather than individual tows, islaid down on a flat or contoured tool (e.g., a stationary or rotatingmandrel) to form the part. One form of tape includes a paper backingthat maintains the width and orientation of the fibers. The paperbacking is removed during application. Slit tape is tape that has beenslit after being produced in standard widths by the manufacturer.Slitting the tape results in narrower widths that allow enhancedstearability and tailoring during application to achieve producibilityand design objectives. Slit tape can have widths varying from about 0.12inch up to about 6 inches, and may or may not include backing paper.Another form of tape includes multiple individual fibers woven togetherwith a cloth material. As used throughout this disclosure, unlessotherwise indicated, the term “tape” refers to tape, tape with backingpaper, slit tape, and other types of composite material in tape form foruse in manufacturing composite structures. Tape laying is often used forparts with highly complex contours or angles because the tape allowsrelatively easy directional changes.

SUMMARY

The present invention is directed generally toward composite sectionsfor aircraft fuselages and other structures, and methods and systems formanufacturing such sections. A system for manufacturing a compositeshell structure in accordance with one aspect of the invention includesa tool and an equipment support member. The equipment support member isconfigured to extend adjacent to a mold surface of the tool. The systemfurther includes a composite material applicator carried by theequipment support member and configured to apply composite material tothe mold surface. In one embodiment of the system, the tool can be alay-up mandrel, and the equipment support member can extend at leastpartially through the lay-up mandrel.

A system for manufacturing a composite shell structure in accordancewith another aspect of the invention includes a first equipment supportmember and a second equipment support member. The first equipmentsupport member is configured to be positioned at least partially withina female tool having an interior mold surface. The second equipmentsupport member is configured to be positioned at least partially outsideof the female tool in operational alignment with the first equipmentsupport member. The system further includes a stiffener placement toolhaving a plurality of stiffener holding portions configured to carry aplurality of corresponding stiffeners. The stiffener placement tool ismovable from the second equipment support member to the first equipmentsupport member to place the plurality of stiffeners at least proximateto the interior mold surface of the female tool. In one embodiment ofthe system, the stiffener placement tool can include at least oneactuator configured to press a portion of the plurality of stiffenersagainst a composite lay-up on the interior mold surface of the femaletool.

A method for manufacturing a shell structure in accordance with afurther aspect of the invention includes applying composite material toan interior mold surface of a tool to form a skin lay-up extending 360degrees around an axis. The method further includes positioning aplurality of stiffeners on an inner surface of the skin lay-up, and atleast partially cocuring the skin lay-up and the plurality of stiffenersto bond the plurality of stiffeners to the skin lay-up. In oneembodiment, the method can additionally include positioning vacuum bagmaterial over the plurality of stiffeners and the skin lay-up, andevacuating a volume under the vacuum bag material to press the pluralityof stiffeners and the skin lay-up outwardly against the interior moldsurface of the tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially hidden isometric view of an aircraft having afuselage that includes a plurality of sections configured in accordancewith an embodiment of the invention.

FIGS. 2A and 2B are an exploded isometric view and an assembledisometric view, respectively, of a portion of a fuselage sectionconfigured in accordance with an embodiment of the invention.

FIGS. 3A and 3B are top and end views, respectively, of a portion of afuselage section configured in accordance with another embodiment of theinvention.

FIGS. 4A and 4B are top and end views, respectively, of a portion of afuselage section configured in accordance with a further embodiment ofthe invention.

FIGS. 5A and 5B are cross-sectional end views of portions of fuselagesections configured in accordance with yet other embodiments of theinvention.

FIG. 6 is a partially schematic isometric view of a composite sectionmanufacturing system configured in accordance with an embodiment of theinvention.

FIG. 7A is an enlarged, partially schematic isometric view of a skinlay-up station of FIG. 6, and FIG. 7B is an enlarged, partiallyschematic side view of the skin lay-up station, configured in accordancewith embodiments of the invention.

FIG. 8A is an enlarged, partially schematic isometric view of astiffener lay-up station of FIG. 6; FIG. 8B is an enlarged,cross-sectional end view of a stiffener placement tool that can be usedin the stiffener lay-up station; and FIGS. 8C-8G are schematic viewsillustrating various steps in a method of placing stiffeners on a skinlay-up in accordance with embodiments of the invention.

FIG. 9A is an enlarged, cross-sectional end view of a temporary vacuumstrip configured in accordance with an embodiment of the invention, andFIG. 9B is a partially cut-away isometric view of a lay-up mandrel forthe purpose of describing a method for vacuum-bagging a lay-up with thetemporary vacuum strip of FIG. 9A.

FIG. 10 is an enlarged, partially schematic isometric view of a debagstation of FIG. 6 configured in accordance with an embodiment of theinvention.

FIG. 11A is an enlarged, partially schematic isometric view of atransfer station of FIG. 6 configured in accordance with an embodimentof the invention, and

FIGS. 11B-11E are partially schematic isometric views illustrating amethod of using the transfer station to remove a shell structure from alay-up mandrel.

FIG. 12 is an enlarged, partially schematic isometric view of a shellstructure parked in a trim station of FIG. 6 in accordance with anembodiment of the invention.

FIG. 13 is an enlarged, partially schematic isometric view of the shellstructure parked in a non-destructive evaluation station of FIG. 6 inaccordance with another embodiment of the invention.

DETAILED DESCRIPTION

The following disclosure describes composite sections for aircraftfuselages and other structures, and methods and systems formanufacturing such sections. Certain details are set forth in thefollowing description and in FIGS. 1-13 to provide a thoroughunderstanding of various embodiments of the invention. Other detailsdescribing well-known structures and systems often associated withaircraft structures and composite fabrication techniques are not setforth in the following disclosure to avoid unnecessarily obscuring thedescription of the various embodiments of the invention.

Many of the details, dimensions, angles, and other features shown in theFigures are merely illustrative of particular embodiments of theinvention. Accordingly, other embodiments can have other details,dimensions, angles, and features without departing from the spirit orscope of the present invention. In addition, further embodiments can bepracticed without several of the details described below.

In the Figures, identical reference numbers identify identical or atleast generally similar elements. To facilitate the discussion of anyparticular element, the most significant digit or digits of anyreference number refer to the Figure in which that element is firstintroduced. For example, element 110 is first introduced and discussedwith reference to FIG. 1.

The following disclosure includes two parts. The first part describescomposite panel structures and associated fuselage sections to provide acontext for the discussion that follows. The second part describesvarious methods and systems for manufacturing composite fuselagesections, such as those described in part one of the disclosure.

I. Composite Sections

FIG. 1 is a partially hidden isometric view of an aircraft 100 having afuselage 102 formed from a plurality of sections 110 in accordance withan embodiment of the invention. In one aspect of this embodimentdescribed in greater detail below, each of the sections 110 can beindividually fabricated as a one-piece section from composite materials.After fabrication, the sections 110 can be joined or spliced together byadhesive bonding and/or mechanical fastening along circumferentialjoints 112 to form the fuselage 102. Various methods, systems, andstructures for joining the sections 110 together are described in detailin copending U.S. patent application Ser. No. 10/949,848, entitled“SPLICE JOINTS FOR COMPOSITE AIRCRAFT FUSELAGES AND OTHER STRUCTURES,”which was filed on Sep. 23, 2004, and is incorporated by reference.

Although the sections 110 are depicted in FIG. 1 as barrel sections orenclosed shell structures extending 360 degrees about an axis, themethods and systems disclosed herein are not limited to this particularconfiguration. Rather, the methods and systems disclosed herein can beused to manufacture other structural configurations including, forexample, open shell structures and non-cylindrical shells havingcircular, oval, elliptical, egg-shaped, and other symmetrical and/orasymmetrical cross-sectional shapes. Such structural configurations alsoinclude curved panels, flat panels, sandwich structures, etc.

In another aspect of this embodiment, the fuselage 102 can include apassenger cabin 104 configured to hold a plurality of passenger seats106. In the illustrated embodiment, the passenger cabin 104 isconfigured to hold at least about 50 passenger seats. For example, inthis embodiment the passenger cabin 104 can be configured to hold fromabout 50 to about 700 passenger seats. In another embodiment, thepassenger cabin 104 can be configured to hold from about 100 to about400 passenger seats. In further embodiments, the passenger cabin 104 canbe configured to hold more or fewer seats or, alternatively, a portionof the passenger seats 106 can be omitted and the open space can be usedfor other purposes, such as hauling cargo.

FIG. 2A is an enlarged, partially exploded, interior isometric view of aportion of one of the sections 110 of FIG. 1, configured in accordancewith an embodiment of the invention. FIG. 2B is an assembled isometricview of the section portion of FIG. 2A. Referring to FIGS. 2A and 2Btogether, the section 110 can include a plurality of stiffeners 230(identified individually as stiffeners 230 a-d) attached to a skin 220.Each of the stiffeners 230 can include a raised portion 234 projectingaway from the skin 220 and a plurality of flange portions 231(identified as a plurality of first flange portions 231 a extendingoutwardly from one side of the stiffener 230, and a plurality of secondflange portions 231 b extending outwardly from an opposite side of thestiffener 230). The flange portions 231 can be mated directly to theskin 220. In the illustrated embodiment, the stiffeners 230 havehat-shaped cross-sections. In other embodiments described below,however, the stiffeners 230 can have other cross-sectional shapesincluding C-sections, L-sections, I-sections, J-sections, etc.

The skin 220 and the stiffeners 230 typically are graphite/epoxycomposites with the stiffeners 230 bonded to the skin 220 in a cocuringprocess at elevated temperatures and pressures. The stiffeners 230 andskin 220, however, can be fastened together in other bonding processes,including adhesive bonding of pre-cured components, mechanicalfastening, or some combination of these processes.

Each stiffener 230 can be positioned on the skin 220 so that theplurality of first flange portions 231 a of one stiffener 230 arealigned with the corresponding plurality of second flange portions 231 bof an adjacent stiffener 230. For example, each of the first flangeportions 231 a can include a first outer edge 233 a, and each of thesecond flange portions 231 b can include a corresponding second outeredge 233 b. In one embodiment, the first outer edge 233 a can be spacedapart from the second outer edge 233 b by a distance D of about 0.5 inchor less. In another embodiment, the distance D can be about 0.2 inch orless, e.g., about 0.1 inch. In yet another embodiment, the stiffeners230 can be positioned on the skin 220 such that the first flangeportions 231 a at least approximately contact the second flange portions231 b. In this case, the distance D is at least approximately zero. Whenthe flange portions 231 are aligned in the foregoing manner, the flangeportions 231 can form a plurality of at least approximately continuoussupport surfaces 235 extending between the raised portions 234 of thestiffeners 230.

The section 110 can further include a plurality of support members orframes 240 (identified individually as a first frame 240 a and a secondframe 240 b). In the illustrated embodiment, the frames 240 aretwo-piece frames that include a first frame section 241 and a secondframe section 242. In this embodiment, the second frame section 242 hasa C-shaped cross-section. In other embodiments, the second frame section242 can have other cross-sectional shapes, such as an L-shapedcross-section. In yet other embodiments, the frames 240 can be omittedor, alternatively, the section 110 can include other frames composed ofmore or fewer frame sections.

The first frame section 241 includes a base portion 244 and anupstanding portion 246 projecting away from the base portion 244. Theupstanding portion 246 can include a plurality of openings, e.g., “mouseholes” 248 through which the raised portions 234 of the stiffeners 230extend. The base portion 244 can include a plurality of mating surfaces243 extending between the mouse holes 248. The mating surfaces 243 areconfigured to contact corresponding ones of the support surfaces 235extending between the raised portions 234 of the stiffeners 230. Themating surfaces 243 of the illustrated embodiment are absent any jogglesbetween the mouse holes 248 because the corresponding support surfaces235 to which they mate are at least approximately continuous between thestiffeners 230 and do not include any significant surface steps ormisalignments. An advantage of this feature is that it avoids the addedcosts associated with manufacturing frames with joggles. Such costs maybe particularly significant when working with composite materialsbecause, unlike creating joggles or steps in metals, which are malleableand can be easily formed, creating joggles or steps in compositesurfaces typically requires special tooling and/or post-cure machining.

In one embodiment of the invention, the first frame section 241 can beattached to the section 110 first, and then the second frame section 242can be attached to the first frame section 241. When attaching the firstframe section 241 to the section 110, the base portion 244 of the firstframe section 241 is mated to the flange portions 231 of the stiffeners230 without being mated to the skin 220. That is, the mating surfaces243 of the base portion 244 contact the support surfaces 235 but not theskin 220. In this manner, the flange portions 231 are effectivelysandwiched between the first frame section 241 and the skin 220. In oneembodiment, the first frame section 241 can be fastened to the section110 with a series of suitable fasteners 252, as shown in FIG. 2B. Inanother embodiment, the base portion 244 can be adhesively bondeddirectly to the flange portions 231.

After the first frame section 241 has been attached to the section 110,the second frame section 242 can be attached to the first frame section241. In one embodiment, the second frame section 242 can be fastened tothe upstanding portion 246 of the first frame section 241 with a seriesof suitable fasteners 250, as shown in FIG. 2A. In another embodiment,the second frame section 242 can be adhesively bonded to the upstandingportion 246. One advantage of attaching the second frame section 242 tothe first frame section 241 after the first frame section 241 has beeninstalled is that the final position of the second frame section 242 canbe adjusted to compensate for any misalignment of the first framesection 241 that may have occurred during installation of the firstframe section 242. In other embodiments, however, the first framesection 241 can be attached to the second frame section 242 first, andthen the frame 240 can be attached to the section 110 as a completeunit.

In another embodiment of the invention, the flange portions 231 of thestiffeners 230 can be at least partially omitted. In this embodiment, araised portion can be formed on the skin 220 between the stiffeners 230with an additional ply or plies of material. The raised portion can takethe place of the flange portions 231 in forming the support surface 235to which the base portion 244 of the first frame section 241 mates.

FIGS. 3A and 3B are top and end views, respectively, of a portion of asection 310 configured in accordance with another embodiment of theinvention. Referring to FIGS. 3A and 3B together, the section 310 caninclude a plurality of first stiffeners 336 and a plurality of secondstiffeners 338 attached to a skin 320. Each of the stiffeners 336 and338 can include a raised portion 334 projecting away from the skin 320.Each of the first stiffeners 336 can further include a first flangeportion 337 a and an opposing second flange portion 337 b that are atleast generally straight. Each of the second stiffeners 338, however,can further include a plurality of first flange portions 331 a and aplurality of opposing second flange portions 331 b that extend outwardlyfrom the raised portion 334 to at least proximate corresponding flangeportions 337 of the adjacent first stiffeners 336. A frame (not shown)can mate to the flange portions 331 and 337 as described with referenceto FIGS. 2A and 2B.

FIGS. 4A and 4B are top and end views, respectively, of a portion of asection 410 configured in accordance with a further embodiment of theinvention. Referring to FIGS. 4A and 4B together, the section 410 caninclude a plurality of asymmetric stiffeners 450 attached to a skin 420.Each of the asymmetric stiffeners 450 can include a plurality of firstflange portions 431 extending outwardly from one side of a raisedportion 434, and a second flange portion 437 extending outwardly from anopposite side of the raised portion 434. The second flange portion 437can be at least approximately straight. The first flange portions 431,however, can project outwardly from the raised portion 434 to at leastproximate the corresponding second flange portion 437 of the adjacentstiffener 450. A frame (not shown) can mate to the flange portions 431and 437 as described with reference to FIGS. 2A and 2B.

FIGS. 5A and 5B are cross-sectional end views of portions of sections510 a and 510 b, respectively, configured in accordance with otherembodiments of the invention. Referring first to FIG. 5A, in one aspectof this embodiment, the section 510 a includes a plurality of I-sectionstiffeners 530 a attached to a skin 520 a. Each of the I-sectionstiffeners 530 a can include a plurality of first flange portions 531 aand a plurality of second flange portions 531 b that are at leastgenerally similar in structure and function to the corresponding flangeportions 231 described with reference to FIGS. 2A and 2B. In anotheraspect of this embodiment, a frame 540 a can mate to the flange portions531 as described with reference to FIGS. 2A and 2B.

Referring next to FIG. 5B, in one aspect of this embodiment, the section510 b includes a plurality of C-section stiffeners 530 b attached to askin 520 b. The C-section stiffeners 530 b can include flange portions531 that are at least generally similar in structure and function to thefirst flange portions 431 described with reference to FIGS. 4A and 4B.In another aspect of this embodiment, a frame 540 b can mate to theflange portions 531 as described with reference to FIGS. 2A and 2B.

Other methods and systems for fabricating the sections 110 are disclosedin copending U.S. patent application Ser. No. 10/851,381, entitled“COMPOSITE SECTIONS FOR AIRCRAFT FUSELAGES AND OTHER STRUCTURES, ANDMETHODS AND SYSTEMS FOR MANUFACTURING SUCH SECTIONS” and filed May 20,2004; Ser. No. 10/853,075, entitled “STRUCTURAL PANELS FOR USE INAIRCRAFT FUSELAGES AND OTHER STRUCTURES” and filed May 25, 2004; andSer. No. 10/819,084, entitled “STRUCTURAL PANELS FOR USE IN AIRCRAFTFUSELAGES AND OTHER STRUCTURES” and filed Apr. 2, 2004; each of which isincorporated by reference.

II. Manufacturing Composite Sections

FIG. 6 is a partially schematic isometric view of a composite sectionmanufacturing system 600 (“manufacturing system 600”) configured inaccordance with an embodiment of the invention. The manufacturing system600 can include a plurality of manufacturing cells or stations forfabricating one-piece composite sections that are at least generallysimilar in structure and function to the fuselage sections 110 describedwith reference to FIGS. 1-5B. For example, the manufacturing system 600can include a skin lay-up station 610, a stiffener lay-up station 620,and a curing station 630. In the skin lay-up station 610, compositematerials are laminated on an inside mold surface 613 of a lay-upmandrel 612 to form a skin lay-up 614. From there, the lay-up mandrel612 proceeds to the stiffener lay-up station 620 where a plurality ofstiffeners 616 are positioned on the skin 614 inside the lay-up mandrel612. The skin 614 and the stiffeners 616 are then vacuum-bagged beforethe lay-up mandrel 612 proceeds on to the curing station 630. At thecuring station 630, the lay-up mandrel 612 is positioned in an autoclave632 to cure the skin/stiffener combination (identified hereinafter asthe “shell 618”).

From the curing station 630, the lay-up mandrel 612 proceeds to a Debagstation 640 where the bagging materials are removed, and then to atransfer station 650. At the transfer station 650, the cured shell 618is removed from the lay-up mandrel 612 and transferred to a trim station660. Window cutouts and other trim operations are carried out at thetrim station 660 before the shell 618 proceeds to a non-destructiveevaluation (NDE) station 670 for acceptance testing. After acceptancetesting, the shell 618 can proceed to other stations (not shown) forinstallation of other structures (e.g., frames, floors, windows, etc.)and systems before final assembly into a complete fuselage.

The configuration of manufacturing stations shown in FIG. 6 is but onearrangement that can be used to manufacture fuselage sections. In otherembodiments, other manufacturing sequences and/or other manufacturingstations can be used in place of or in addition to one or more of themanufacturing stations illustrated in FIG. 6. Operations shown as beingperformed at a single station might be broken into multiple stationsdoing subtasks, respectively, or illustrated stations might be combinedso that what are shown as separate subtasks are done at a single worklocation.

FIG. 7A is an enlarged, partially schematic isometric view of the skinlay-up station 610 of FIG. 6 with the lay-up mandrel 612 removed forclarity. FIG. 7B is an enlarged, partially schematic side view of theskin lay-up station 610 for the purpose of describing a skin lay-upprocess in accordance with an embodiment of the invention. Referring toFIGS. 7A and 7B together, in one aspect of this embodiment, the skinlay-up station 610 includes a first stanchion 740 spaced apart from asecond stanchion 742. The first stanchion 740 supports an equipmentsupport member or boom 744 that extends outwardly from the firststanchion 740 toward the second stanchion 742. The first stanchion 740is longitudinally movable in both +L and −L directions to position theequipment boom 744 as needed relative to the lay-up mandrel 612. Whenthe equipment boom 744 is fully inserted through the lay-up mandrel 612,a distal end 745 is supported by a journal 746 on the second stanchion742.

The equipment boom 744 can support a plurality of apparatuses forapplying composite materials to the inside mold surface 613 of thelay-up mandrel 612. In the illustrated embodiment, these apparatusesinclude a tackifier dispenser 752, a fabric dispenser 754, a pluralityof tape lay-up machines 756 (identified individually as tape lay-upmachines 756 a-f), and a plurality of doubler lay-up machines 758(identified individually as doubler lay-up machines 758 a-b). All ofthese apparatuses are configured to move longitudinally in both the +Land −L directions along the equipment boom 744. In addition, theseapparatuses are further configured to rotate circumferentially in both+C and −C directions relative to the boom axis. A counterbalance 752 canbe used to counterbalance one or more of the apparatuses supported bythe equipment boom 744 on the opposite side of the first stanchion 740if needed to longitudinally and/or rotationally offset the weight ofthese apparatus as they move about on the equipment boom 744.

The tackifier dispenser 752 is configured to dispense a thinned epoxyresin or other tacky agent (i.e., “tackifier”) onto the mold surface 613prior to laying down composite material. The tackifier helps the firstply of material temporarily adhere to the mold surface 613 during thelay-up process. As mentioned above, the tackifier dispenser 752 can movelongitudinally in the +/−L directions along the equipment boom 744 todispense tackifier. In addition, the tackifier dispenser 752 can alsorotate circumferentially about the equipment boom 744 in the +/−Cdirections.

The fabric dispenser 754 is configured to apply composite fabric to themold surface 613. In one embodiment, for example, the fabric dispensercan dispense pre-impregnated, bidirectional woven cloth, such asgraphite-epoxy cloth, having a trimmed width of about 42 inches. Inother embodiments, the fabric dispenser can lay down other types ofcomposite materials having other widths and/or other weave patterns.Like the tackifier dispenser 752, the fabric dispenser 754 can rotatecircumferentially about the equipment boom 744 to apply fabric to themold surface 613 in a spiral pattern or as a series of circumferentialsections. In selected embodiments, however, it may also be advantageousto apply fabric in a longitudinal pattern. In such embodiments, thefabric dispenser 754 can be pivoted 90 degrees in a P direction as shownin FIG. 7A to orient the fabric dispenser 754 parallel to the equipmentboom 744. In this orientation, the fabric dispenser 754 can apply fabricto the mold surface 613 in the longitudinal +/−L directions bytranslating back and forth on the equipment boom 744.

The tape lay-up machines 756 can include commercially available tapeheads configured to apply preimpregnated tape to the mold surface 613.Each of the tape lay-up machines 756 is supported on a separate gantryrail 757. The gantry rails 757 allow the tape lay-up machines 756 tomove independently of each other in the +/−C directions. The tape lay-upmachines 756 can also move independently of each other in the +/−Ldirections. In one embodiment, the tape lay-up machines can apply tapehaving a width from about 3 inches to about 12 inches, e.g., about 6inches. In other embodiments, the tape can have other widths dependingon various factors including coverage, stearability, etc. If the tape issix inches wide, then the individual tape lay-up machines 756 can belongitudinally offset from each other in six-inch increments. Thisspacing enables the plurality of tape lay-up machines 756 to apply acontinuous layer of tape by first applying tape circumferentially at onelongitudinal station, and then moving six inches to the nextlongitudinal station.

In another embodiment, the individual tape lay-up machines 756 can alsobe circumferentially staggered with respect to each other. In thisembodiment, the tape lay-up machines 756 can then be moved parallel tothe equipment boom 744 to apply tape to the lay-up in a longitudinalpattern. In the illustrated embodiment, the gantry rails 757 do notextend a full 360 degrees around the equipment boom 744. Accordingly,the gantry rails 757 can be configured to rotate circumferentially inthe +/−C directions as necessary to provide tape head access to theentire mold surface 613. Additionally, the equipment boom 744 can alsobe configured to rotate in the +/−C directions as necessary to achievethis goal.

Although six of the tape lay-up machines 756 are shown in FIGS. 7A-B forpurposes of illustration, in other embodiments, more or fewer tapelay-up machines can be used depending on a number of different factors.For example, if higher speed is desired, then more tape lay-up machinescan be employed. In contrast, if speed is less important, then fewertape lay-up machines 756 can be used.

Each of the doubler lay-up machines 758 is supported on a separategantry rail 757 in the same manner as the tape lay-up machines 756 and,accordingly, can move in similar directions. In the illustratedembodiment, the doubler lay-up machines 758 include commerciallyavailable cassette heads configured to place pre-cut doublers and/ordoubler segments onto the lay-up inside the lay-up mandrel 612. In oneembodiment, the doubler lay-up machines 758 can be loaded with precutdoublers as follows: First, tape is laid down on a work table andtrimmed to a desired doubler size. The tape is then re-rolled back ontoa cassette. Next, the cassette is loaded onto one of the doubler lay-upmachines 758. When a doubler is needed during the lay-up process (forexample, for placement around a window cutout), the doubler lay-upmachines 758 move into position and dispense the doubler at the desiredlocation. In this manner, doublers can be interleaved with tape pliesduring the lay-up process. Although two doubler lay-up machines 758 areillustrated in FIGS. 7A-B, in other embodiments, more or fewer doublerlay-up machines can be used as required.

As shown in FIG. 7B, the lay-up mandrel 612 is supported in a fixture708. The fixture 708 can rotate the lay-up mandrel 612 in the +/−Cdirections as required to facilitate any of the lay-up operationsdescribed above.

To lay-up a skin on the mold surface 613, the lay-up mandrel 612 ismoved into the skin lay-up station 610 and aligned with the equipmentboom 744. Next, the equipment boom 744 is inserted through the lay-upmandrel 612 and engaged with the second stanchion 742. The tackifierdispenser 752 then moves into the lay-up mandrel 612 and appliestackifier to the mold surface 613. Once tackifier has been applied, thetackifier dispenser 752 moves out of the lay-up mandrel 612 in the +Ldirection and is parked next to the second stanchion 742.

Next, the fabric dispenser 754 moves into the lay-up mandrel 612 andlays down an OML ply of fabric on the mold surface 613. As explainedabove, after applying a circumferential row of fabric at onelongitudinal station, the fabric dispenser 754 can move a presetincrement in the longitudinal direction to apply the next row of fabric.In addition or alternatively, the fabric dispenser 754 can pivot in theP direction (FIG. 7A) to lay down fabric in longitudinal rows. In theforegoing manner, the fabric dispenser 754 can lay down a complete OMLply of fabric on the mold surface 613. If additional plies of fabric aredesired, they can be laid down over the OML ply in the manner describedabove. After the fabric dispenser 754 has laid down the desired numberof plies, it moves out of the lay-up mandrel 612 in the +L direction andis parked next to the tackifier dispenser 752 by the second stanchion742.

The tape lay-up machines 756 move into the lay-up mandrel 612 after thefabric dispenser 754. As explained above, tape can be applied to thefabric lay-up by movement of the tape lay-up machines 756 in both thecircumferential and longitudinal directions. Doublers can be applied indesired locations by temporarily parking the tape lay-up machines 756next to the second stanchion 742 and moving one or more of the doublerlay-up machines 758 into the lay-up mandrel 612. In this manner, thetape lay-up machines 756 and the doubler lay-up machines 758 can move inand out of the lay-up mandrel as required to interleave the doublerswith the tape plies.

Once the tape and doubler plies have been laid up, the doubler lay-upmachines 758 and the tape lay-up machines 756 are moved out of thelay-up mandrel 612 in the −L direction and parked next to the firststanchion 740. The fabric dispenser 754 then moves back into the lay-upmandrel 612 to lay an IML ply of fabric on the lay-up. During any partof the lay-up process described above, the fixture 708 can rotate thelay-up mandrel 612 in the +/−C directions as required to facilitateapplication of the various composite materials. Once the lay-up processis complete, the equipment boom 744 is extracted and the lay-up mandrel612 is moved to the stiffener lay-up station 620 (FIG. 6).

One feature of the lay-up process described above is that all of thecomposite materials are applied directly to the inside mold surface 613of the lay-up mandrel 612. One advantage of this feature is that iteliminates the need for a winding mandrel or other male tool having anexterior mold surface. In addition, it also eliminates the need forouter caul plates or other devices to provide the finished part with asmooth exterior surface. The process described above also allows directdoubler placement.

The lay-up process described above is not limited to the application ofcomposite fabric, tape, and/or doublers. Accordingly, in otherembodiments, other types of composite materials can be applied to themold surface 613 to form the skin lay-up. Such materials can include,for example, fiber tows (e.g., 0.25-0.50 inch wide fiber tows) appliedusing suitable fiber placement tools and methods. The fiber placementtools can be moved into the lay-up mandrel 612 on the equipment boom 744using methods similar to those described above for the fabric dispenser754 and the tape lay-up machines 756.

FIG. 8A is an enlarged, partially schematic isometric view of thestiffener lay-up station 620 of FIG. 6 configured in accordance with anembodiment of the invention. The lay-up mandrel 612 is not shown in FIG.8A for purposes of clarity. FIG. 8B is an enlarged, cross-sectional endview of a stiffener placement tool 860 c that is used in the stiffenerlay-up station 620. FIG. 8C is a partially schematic, cross-sectionalside view, and FIGS. 8D-G are partially schematic end views, of thestiffener lay-up station 620 illustrating various steps in a method ofplacing stiffeners on a skin lay-up in accordance with an embodiment ofthe invention. Referring first to FIG. 8A, the stiffener lay-up station620 includes a first stanchion 840 that is movable relative to a secondstanchion 842. The first stanchion 840 supports an equipment supportmember or mandrel boom 844 that can be rotated in the +/−C directions bya first drive assembly 850 a. The mandrel boom 844 supports a pluralityof utility rails 852 (identified as utility rail pairs 852 a-d).

The second stanchion 842 supports a stiffener boom 845 that is rotatablein the +/−C directions by a second drive assembly 850 b. The stiffenerboom 845 supports a plurality of stiffener placement tools 860(identified individually as stiffener placement tools 860 a-d). Each ofthe stiffener placement tools 860 carries a set of the stiffeners 616(identified individually as stiffener sets 616 a-d) that are positionedon the skin 614 (FIG. 6) during the stiffener lay-up process. Further,each of the stiffener placement tools 860 can be independentlytransferred from the stiffener boom 845 to the mandrel boom 844 forstiffener placement.

The stiffener lay-up station 620 further includes a bag assist tool 870.The bag assist tool 870 includes a bag boom 874 which carries aplurality of vacuum bag dispensers 876 on bag support rails 872. The bagassist tool 870 is configured to be aligned with the first stanchion 840so that one or more of the vacuum bag dispensers 876 can be transferredfrom the bag support rails 872 to an aligned pair of the utility rails852.

FIG. 8B is an enlarged, cross sectional end view of the third stiffenerplacement tool 860 c of FIG. 8A configured in accordance with anembodiment of the invention. In one aspect of this embodiment, thestiffener placement tool 860 c includes a plurality of stiffenerpositioners 864 (identified individually as stiffener positioners 864a-c) attached to a subframe 863 by a plurality of actuators 865(identified individually as actuators 865 a-c). The subframe 863slidably mounts to a pair of corresponding stiffener support rails 862which are carried in turn by the stiffener boom 845. The other stiffenerplacement tools 860 a, b and d are at least generally similar instructure and function to the third stiffener placement toot 860 c.

Each of the stiffener positioners 864 includes a plurality of holdingportions 866 configured to receive and support the third set ofstiffeners 616 c during the placement process. In the illustratedembodiment, the stiffeners 616 c are hat section stiffeners and theholding portions 866 are configured accordingly. In other embodiments,however, the stiffener positioners 864 can be configured to supportother types of stiffeners for placement on the skin 614. Such stiffenersinclude, for example, I-section stiffeners, C-section stiffeners,Z-section stiffeners, etc.

The stiffeners 616 c can be uncured, partially cured, or fully curedwhen they are positioned in the holding portions 866. If uncured orpartially cured, then mandrels 868 can be positioned inside thestiffeners 616 c to keep the stiffeners 616 c from collapsing underpressure during the subsequent vacuum-bagging and curing cycles. In thisregard, the mandrels 168 can be inflatable mandrels that are deflatedafter the cure cycle for removal. Alternatively, the mandrels 868 can be“fly-away” mandrels or rigid or semi-rigid mandrels that can bephysically or chemically removed after the cure cycle. If the stiffeners616 c are fully cured when they are positioned in the holding portions866, then internal support during the subsequent vacuum-bagging andcuring cycles may not be needed. However, additional adhesive may berequired to bond the cured stiffeners 616 c to the skin 614 during thecuring cycle. Once the mandrels 868 have been installed in each of thestiffeners 616 c, a temporary strap 861 can be placed over thestiffeners to temporarily hold them in place prior to installationinside the lay-up mandrel 612. In one embodiment, the straps 861 can bemade from Teflon or a Teflon-coated material, such as Armalon.

As described in greater detail below with reference to FIG. 8C, thestiffener placement tool 860 c is able to move in the +/−L directions onthe stiffener support rails 862 c to position the stiffeners 616 cinside the lay-up mandrel 612. Once inside the lay-up mandrel 612, thetemporary strap 861 can be removed and the actuators 865 can be extendedto press the stiffeners 616 c against the skin 614. In one embodiment,the actuators 865 can include air cylinders that can be controlled toextend and retract axially in direction R. In other embodiments, otherapparatuses can be used to move the stiffeners 616 c radially outwardlytoward the mold surface 613. Such apparatuses can include, for example,various mechanical, pneumatic, electromechanical, and hydraulic devices.

Referring to FIG. 8C, the lay-up mandrel 612 is aligned with thestiffener boom 845, and the mandrel boom 844 is inserted through thelay-up mandrel 612 and coupled to the stiffener boom 845. The bag assisttool 870 is positioned behind the first stanchion 840 so that the bagboom 874 is aligned with the mandrel boom 844. In the foregoingarrangement, each of the stiffener support rails 862 on the stiffenerboom 845 is aligned with a corresponding utility rail 852 on the mandrelboom 844. In addition, each of the bag support rails 872 on the bag boom874 is also aligned with a corresponding utility rail 852. Thisalignment enables the stiffener positioning tools 860 and the vacuum bagdispensers 876 to move in and out of the lay-up mandrel 612 on theutility rails 852.

FIGS. 8D-G are cross-sectional end views of the lay-up mandrel 612 takenalong line 8D-G-8D-G in FIG. 8C for the purpose of describing varioussteps in a method for placing the stiffeners 616 on the skin 614.Referring first to FIGS. 8B-D together, the first stiffener placementtool 860 a is transferred from the first pair of stiffener support rails862 a to the first pair of utility rails 852 a to move the firststiffener placement tool 860 a into the lay-up mandrel 612. Once thefirst stiffener placement tool 860 a is fully positioned in the lay-upmandrel 612, the actuators 865 are extended to position the first set ofstiffeners 616 a just above the skin 614. At this point, the straps 861(FIG. 8B) which were temporarily holding the stiffeners 616 a in placecan be removed. Next, the actuators 865 are further extended to pressthe stiffeners 616 a firmly against the skin 614. The actuators 865 canthen be retracted, leaving the stiffeners 616 a (and the associatedmandrels 868) in position on the skin 614. The first stiffener placementtool 860 a can then be moved back onto the stiffener boom 845 via thefirst pair of stiffener support rails 862 a.

Once the first stiffener placement tool 860 a has been removed from thelay-up mandrel 612, a release layer (not shown) can be laid over thefirst set of stiffeners 616 a, and a breather layer (also not shown) canbe laid over the release layer, as is standard practice. Suitablerelease layers include fluorinated ethylene-propylene (FEP), andvirtually any loosely woven or similar material can be used to providethe continuous vacuum path of the breather layer. As shown in FIG. 8E,one or more work platforms 873 can be moved into the lay-up mandrel 612on the utility rails 852 a to facilitate manual installation of therelease and breather layers. At this time, temporary vacuum strips 880are positioned on the skin 614 on each side of the first set ofstiffeners 616 a. The temporary vacuum strips 880 run the full length ofthe lay-up mandrel 612. The structure and function of the temporaryvacuum strips 880 are described in greater detail below with referenceto FIGS. 9A-B.

After the temporary vacuum strips have been installed, one of the vacuumbag dispensers 876 is moved into the lay-up mandrel 612 on the utilityrails 852 a, as shown in FIG. 8F. Bagging material 885 is then manuallypositioned over the first set of stiffeners 616 a on the breather layer.The bagging material 885 is sealed around the periphery of the first setof stiffeners 616 a by means of the temporary vacuum strips 880 on thesides, and by other sealing means (e.g., vacuum bag sealing tape) on theends of the lay-up mandrel 612. The volume beneath the bag material 885is then evacuated to press the stiffeners 616 a against the skin 614.

Referring next to FIG. 8G, once the bagging material 885 has beenevacuated, the first stiffener placement tool 860 a is reinserted intothe lay-up mandrel 612 and repositioned over the first set of stiffeners616 a. The actuators 865 are then extended to hold the stiffeners 616 ain place against the skin 614 as a back-up for the vacuum pressure.Next, the lay-up mandrel 612 is rotated 90 degrees in the −C directionso that the second stiffener placement tool 860 b can be inserted intothe lay-up mandrel 612. The second set of stiffeners 616 b is theninstalled in the same manner described for the first set of stiffeners616 a. Prior to installing the, associated bagging material, however,the temporary vacuum strip 880 between the first set of stiffeners 616 aand the second set of stiffeners 616 b is removed and the bags aresealed together. The foregoing processes are then repeated for the thirdset of stiffeners 616 c and the fourth set of stiffeners 616 d until allof the stiffeners 616 have been positioned in the lay-up mandrel 612 andthe entire lay up has been vacuum-bagged. The process of sealing the bagsections together is described in more detail below with reference toFIGS. 9A-B.

FIG. 9A is an enlarged, cross-sectional end view of one of the temporaryvacuum strips 880 configured in accordance with an embodiment of theinvention. FIG. 9B is a partially cut-away isometric view of the lay-upmandrel 612 for the purpose of describing a method for vacuum-bagging alay-up with the temporary vacuum strips 880 in accordance with anotherembodiment of the invention. Referring first to FIG. 9A, each of thetemporary vacuum strips 880 is divided into a first chamber 982 a and asecond chamber 982 b. A first plurality of holes 984 a extend through afirst sidewall 983 a of the first chamber 982 a, and a second pluralityof holes 984 b extend through a second sidewall 983 b of the secondchamber 982 b. In the illustrated embodiment, the temporary vacuumstrips 880 can be made from an elastic material such as rubber,polyurethane, plastic, etc. that flexes under pressure but returns toits original shape when the pressure is removed.

Referring next to FIG. 9B, prior to installation of the bagging material885, the temporary vacuum strips 880 (identified individually as a firsttemporary vacuum strip 880 a and a second temporary vacuum strip 880 b)are positioned outboard of the first set of stiffeners 616 a with thefirst chambers 982 a (FIG. 9A) facing the skin 614. The first chambers982 a are then evacuated, creating a suction force which holds thetemporary vacuum strips 880 in position against the skin 614. Next, thebagging material 885 (identified as a first portion of bagging material885 a for ease of reference) is laid over the stiffeners 616 and thetemporary vacuum strips 880. (Release and breather layers are not shownin FIG. 9A for purposes of clarity.) Once the bagging material 885 hasbeen properly positioned, the second chambers 882 b of the vacuum strips880 can be evacuated to seal the bagging material 885 against thetemporary vacuum strips 880. Although not illustrated in FIG. 9B, thebagging material 885 can be sealed at the respective ends of the lay-upmandrel 612 using additional temporary vacuum strips 880, conventionalsealing tape, or an equivalent medium. Once the bagging material 885 hasbeen fully sealed around the first set of stiffeners 616 a, it can beevacuated to press the stiffeners 616 a against the skin 614.

After the first set of stiffeners 616 a has been vacuum-bagged, thesecond set of stiffeners 616 b (FIG. 8G) can be installed in the lay-upmandrel 612 adjacent to the first set 616 a on the opposite side of thesecond temporary vacuum strip 880 b. To install a second portion ofbagging material 885 (not shown) over the second set of stiffeners 616b, a third temporary vacuum strip 880 (also not shown) is installed onthe skin 614 on the side of the second set of stiffeners 616 b oppositeto the second temporary vacuum strip 880 b. Next, the second portion ofbagging material 885 is sealed to the third temporary vacuum strip 880in the manner described above. The first portion of bagging material 885a is then released from the second temporary vacuum strip 880 b, and thesecond temporary vacuum strip 880 b is removed from the skin 614 byreleasing the suction in the corresponding chambers 982. Removing thesecond temporary vacuum strip 880 b enables the second portion ofbagging material 885 to be sealed to the first portion of baggingmaterial 885 a (with, for example, conventional sealing tape) to providea continuous bag over the first and second stiffener sets 616 a-b. Theremaining stiffener sets 616 c-d, and the corresponding portions ofbagging material 885, can then be sequentially installed in the lay-upmandrel 612 using the steps outlined above for the first and secondstiffener sets 616 a-b. Accordingly, when the last portion of baggingmaterial 885 is installed, the final temporary vacuum strip 880 can beremoved from the lay-up mandrel 612 to provide a continuous vacuum bagover the entire skin/stiffener lay-up (i.e., over the entire shell 618(FIG. 6)).

Referring momentarily back to FIG. 6, after the shell 618 has beenvacuum-bagged as described with reference to FIGS. 8A-G, the lay-upmandrel 612 is moved to the curing station 630 and positioned in theautoclave 632. The shell 618 is then cured by elevating the temperatureand pressure inside the autoclave 632 for a preset period of time. Forexample, in one embodiment, the shell 618 can be cured by raising thetemperature to 350 degrees Fahrenheit and the pressure to 85 psi for aperiod of about two hours. In other embodiments, other curing parameterscan be used depending on various factors including material type,equipment and facilities limitations, etc. In one other embodiment, forexample, the shell 618 can be cured in an oven at an elevatedtemperature without a substantial increase in pressure. In furtherembodiments using appropriate materials, the shell 618 can be cured atambient temperatures and/or ambient pressures. In yet other embodiments,temporary headers and/or other similar structures can be used to provideadditional support to the shell 618 during the cure cycle to maintain,e.g., stiffener positions.

FIG. 10 is an enlarged, partially schematic isometric view of the debagstation 640 of FIG. 6 configured in accordance with an embodiment of theinvention. In one aspect of this embodiment, the debag station 640includes a first stanchion 1040 spaced apart from a second stanchion1042. The first stanchion 1040 supports a debag boom 1044 which in turncarries work platforms 1073 and a release agent dispenser 1052. When thelay-up mandrel 612 comes to the debagging station 640 from the autoclave632, the debag boom 1044 is inserted through the lay-up mandrel 612 andengaged with the second stanchion 1042. Factory technicians can thenenter the lay-up mandrel 612 on the work platforms 1073 to remove thebagging material 885 from the shell 618.

Once the shell 618 has been removed from the lay-up mandrel 612 at thetransfer station 650 (FIG. 6), the lay-up mandrel 612 can return to thedebag station 640 for the application of Frekote® or other suitablerelease agent. The release agent dispenser 1052 is configured to moveback and forth in the +/−L directions and to rotate circumferentially inthe +/−C directions to apply the release agent to the entire moldsurface 613. In addition, as mentioned above, the lay-up mandrel 612 canalso be rotated in the +/−C directions if needed to facilitate releaseagent application. The release agent is applied to the mold surface 613before the lay-up mandrel 612 is returned to the skin lay-up station 610(FIG. 6) to prevent the next skin lay-up from bonding to the moldsurface.

FIG. 11A is an enlarged, partially schematic isometric view of thetransfer station 650 of FIG. 6 configured in accordance with anembodiment of the invention. In one aspect of this embodiment, thetransfer station 650 includes a header boom 1144 cantilevered from afirst stanchion 1140. The header boom 1144 supports a plurality ofcircumferentially expandable headers 1152 configured to fit inside thelay-up mandrel 612 (not shown in FIG. 11A). The first stanchion 1140 ismovable in the +/−L directions to engage/disengage the header boom 1144with a second stanchion 1142. In another aspect of this embodiment, thetransfer station 650 further includes a first gantry 1190 a and a secondgantry 1190 b. The gantries 1190 are configured to lift various portionsof the lay-up mandrel 612 and/or the header boom 1144, and move themback and forth in the +/−L directions on tracks 1194.

FIGS. 11B-E are partially schematic isometric views illustrating amethod for removing the shell 618 from the lay-up mandrel 612 at thetransfer station 650. To facilitate this process, the lay-up mandrel 612is separable into a first mandrel half 1112 a and a second mandrel half112 b. Referring first to FIG. 11B, the lay-up mandrel 612 is alignedwith the second stanchion 1142, and the header boom 1144 is insertedthrough the lay-up mandrel 612 and engaged with the second stanchion1142. The headers 1152 are then expanded outwardly against the shell 618to provide support. Next, the second gantry 1190 b is moved in the −Ldirection and positioned over the lay-up mandrel 612. Lifting devices(not shown) extend downwardly from the second gantry 1190 b and lift thefirst mandrel half 1112 a off of the second mandrel half 1112 b. Thesecond gantry 1190 b then moves back in the +L direction and parks inthe position shown in FIG. 11B.

Referring now to FIG. 11C, the first gantry 1190 a moves in the +Ldirection into position over the shell 618. Lifting devices then extenddownwardly from the first gantry 1190 a and engage the ends of theheader boom 1144. The first gantry 1190 a then lifts the header boom1144 upwardly and out of the second mandrel half 1112 b. Referring nextto FIG. 11D, the first gantry 1190 a then moves the header boom 1144 inthe −L direction to, make room for the second gantry 1190 b. The secondgantry 1190 b moves into position and lowers the first mandrel half 1112a downwardly onto the second mandrel half 1112 b. The two mandrel halves1112 are then reattached, and the lay-up mandrel 662 is returned to thedebag station 640 for application of release agent as described withreference to FIG. 10. As shown in FIG. 11E, the first gantry 1190 a thenlowers the header boom 1144 down onto a transport dolly 1196. Thetransport dolly 1196 then carries the shell 618 from the transferstation 650 to the trim station 660.

FIG. 12 is an enlarged, partially schematic isometric view of the shell618 parked in the trim station 660 of FIG. 6. The trim station 660 caninclude a plurality of arched gantry tracks 1282 which extend over theshell 618 and are movable in the +/−L directions. A plurality of cuttingdevices 1280 (e.g., numerically controlled drill routers) are mounted tothe gantry tracks 1282 and are configured to move back and forth in thecircumferential +/−C directions. The cutting devices 1280 can beautomatically controlled (by, e.g., an associated computer program) totrim the ends of the shell 618 and provide window cutouts and otherapertures according to a preset plan. The header boom 1144 can berotated in the +/−C directions if needed to facilitate the varioustrimming operations. After the shell 618 has been fully trimmed, thetransport dolly 1196 proceeds to the NDE station 670.

FIG. 13 is an enlarged, partially schematic isometric view of the shell618 parked in the NDE station 670 of FIG. 6. The NDE station 670 caninclude a plurality of arched gantry tracks 1382 that are at leastgenerally similar in structure and function to the gantry tracks 1282 ofFIG. 12. In the illustrated embodiment, however, the gantry tracks 1382can support a plurality of nondestructive test devices 1384 forperforming acceptance tests on the shell 618. In one embodiment, forexample, the test devices 1384 can include pulse-echo sensors forultrasonically testing the skin 614 for voids and/or other manufacturingdefects. To test the stiffeners 616 on the inside of the skin 614, aseparate set of sensors positioned inside the shell 618 may be required.In other embodiments, other devices can be used to assess the structuraland/or dimensional integrity of the shell 618. Such devices can include,for example, x-ray, infrared, and laser sensors, as well as variousother known test devices.

Once the shell 618 has been fully evaluated, the header boom 1144 islifted out of the transport dolly 1196 to position the shell 618 in acradle or other suitable fixture. The headers 1152 can then be retractedinwardly so that the header boom 1144 can be extracted from the shell618. Final assembly of the shell 618 can then proceed with theinstallation of frames, floors, doors, windows, and other structures andsystems. At some point in the final assembly process, the shell 618 isjoined to adjacent fuselage sections form an entire fuselage structureat least generally similar in structure and function to the fuselage 102shown in FIG. 1.

The subject matter of copending U.S. patent application Ser. Nos.10/646,509, entitled “MULTIPLE HEAD AUTOMATED COMPOSITE LAMINATINGMACHINE FOR THE FABRICATION OF LARGE BARREL SECTION COMPONENTS,” filedAug. 22, 2003; 10/717,030, entitled “METHOD OF TRANSFERRING LARGEUNCURED COMPOSITE LAMINATES,” filed Nov. 18, 2003; 10/646,392, entitled“AUTOMATED COMPOSITE LAY-UP TO AN INTERNAL FUSELAGE MANDREL,” filed Aug.22, 2003; 10/630,594, entitled “COMPOSITE FUSELAGE MACHINE,” filed Jul.28, 2003; 10/646,316, entitled “UNIDIRECTIONAL, MULTI-HEAD FIBERPLACEMENT,” filed Aug. 22, 2003; 10/301,949, entitled “PARALLELCONFIGURATION COMPOSITE MATERIAL FABRICATOR,” filed Nov. 22, 2002;10/799,306, entitled “SYSTEMS AND METHODS ENABLING AUTOMATED RETURN TOAND/OR REPAIR OF DEFECTS WITH A MATERIAL PLACEMENT MACHINE,” filed Mar.12, 2004; 10/726,099, entitled “SYSTEMS AND METHODS FOR DETERMININGDEFECT CHARACTERISTICS OF A COMPOSITE STRUCTURE,” filed Dec. 2, 2003;10/628,691, entitled “SYSTEMS AND METHODS FOR IDENTIFYING FOREIGNOBJECTS AND DEBRIS (FOD) AND DEFECTS DURING FABRICATION OF A COMPOSITESTRUCTURE,” filed Jul. 28, 2003; and 10/822,538, entitled “SYSTEMS ANDMETHODS FOR USING LIGHT TO INDICATE DEFECT LOCATIONS ON A COMPOSITESTRUCTURE, filed Apr. 12, 2004, is incorporated by reference. Inaddition, the subject matter of U.S. Pat. No. 6,168,358 is alsoincorporated by reference.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the invention. For example, aspects of the inventiondescribed in the context of particular embodiments may be combined oreliminated in other embodiments. Further, while advantages associatedwith certain embodiments of the invention have been described in thecontext of those embodiments, other embodiments may also exhibit suchadvantages, and no embodiment need necessarily exhibit such advantagesto fall within the scope of the invention. Accordingly, the invention isnot limited, except as by the appended claims.

1-34. (canceled)
 35. A stiffener positioning tool for positioningstiffeners relative to a mold surface, the tool comprising: at least onestiffener positioner, the stiffener positioner having a plurality ofstiffener holding portions configured to carry a plurality ofcorresponding stiffeners; and at least one actuator operably coupled tothe stiffener positioner, wherein the actuator is configured to move thestiffener positioner and press the plurality of stiffeners against themold surface.
 36. The stiffener positioning tool of claim 35 wherein theplurality of stiffener holding portions includes a plurality of elongatechannels arranged in parallel to each other.
 37. The stiffenerpositioning tool of claim 35 wherein the plurality of stiffener holdingportions are configured to carry the plurality of correspondingstiffeners in a non-planar arrangement.
 38. The stiffener positioningtool of claim 35 wherein the at least one actuator is configured to movethe stiffener positioner and press the plurality of stiffeners against acurved mold surface.
 39. The stiffener positioning tool of claim 35wherein the mold surface extends for 360 degrees around an axis, andwherein the at least one actuator is configured to press the pluralityof stiffeners outwardly against the mold surface.
 40. The stiffenerpositioning tool of claim 35 wherein the plurality of stiffener holdingportions are configured to carry a plurality of composite hat-sectionstiffeners.
 41. The stiffener positioning tool of claim 35 wherein theat least one stiffener positioner is a first stiffener positioner havinga first plurality of stiffener holding portions configured to carry afirst plurality of corresponding stiffeners, wherein the at least oneactuator is a first actuator, and wherein the tool further comprises: asecond stiffener positioner positioned adjacent to the first stiffenerpositioner, the second stiffener positioner having a second plurality ofstiffener holding portions configured to carry a second plurality ofcorresponding stiffeners; and a second actuator operably coupled to thesecond stiffener positioner, wherein the second actuator is configuredto move the second stiffener positioner and press the second pluralityof corresponding stiffeners against the mold surface. 42-80. (canceled)